Dual axle robotic end effector

ABSTRACT

An end effector includes a distal clevis, an axle mounted to the distal clevis, a first jaw holder and corresponding first jaw member rotatably mounted to the axle, and second jaw holder and corresponding second jaw member rotatably mounted to the axle. A cylindrical sleeve axle having opposing first and second ends and defining a central passageway extending between the opposing first and second ends, the sleeve axle providing a continuously straight and uninterrupted outer surface extending entirely between the opposing first and second ends. The axle is received within the central passageway and the sleeve axle is rotatable relative to the axle.

BACKGROUND

Minimally invasive surgical (MIS) instruments are often preferred overtraditional open surgical devices due to reduced post-operative recoverytime and minimal scarring. Laparoscopic surgery is one type of MISprocedure in which one or more small incisions are formed in the abdomenof a patient and a trocar is inserted through the incision to form apathway that provides access to the abdominal cavity. Through thetrocar, a variety of instruments and surgical tools can be introducedinto the abdominal cavity. The trocar also helps facilitate insufflationto elevate the abdominal wall above the organs. The instruments andtools introduced into the abdominal cavity via the trocar can be used toengage and/or treat tissue in a number of ways to achieve a diagnosticor therapeutic effect.

Various robotic systems have recently been developed to assist in MISprocedures. Robotic systems can allow for more intuitive hand movementsby maintaining natural eye-hand axis. Robotic systems can also allow formore degrees of freedom in movement by including a “wrist” joint thatcreates a more natural hand-like articulation. Although not necessary,the instrument's end effector can be articulated (moved) using a cabledriven motion system having one or more drive cables that extend throughthe wrist joint. A user (e.g., a surgeon) is able to remotely operate aninstrument's end effector by grasping and manipulating in space one ormore controllers that communicate with a tool driver coupled to thesurgical instrument. User inputs are processed by a computer systemincorporated into the robotic surgical system and the tool driverresponds by actuating the cable driven motion system and, moreparticularly, the drive cables. Moving the drive cables articulates theend effector to desired positions and configurations.

To ensure accurate and responsive end effector articulation, the drivecables are maintained at elevated tensile loads. At such elevatedtensile loads, the axle that governs articulation of the end effector inyaw motion can begin to gall, which can generate excess friction andcontribute to cable breakage. Galling of the axles is exacerbated in endeffectors having opposing jaws or blades with jaw holders that rotateindependently against the axle. Galling between the axle and the jawholders increases friction, which reduces cable life.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of thepresent disclosure, and should not be viewed as exclusive embodiments.The subject matter disclosed is capable of considerable modifications,alterations, combinations, and equivalents in form and function, withoutdeparting from the scope of this disclosure.

FIG. 1 is a block diagram of an example robotic surgical system that mayincorporate some or all of the principles of the present disclosure.

FIG. 2 is a side view of an example surgical tool that may incorporatesome or all of the principles of the present disclosure.

FIG. 3 illustrates potential degrees of freedom in which the wrist ofFIG. 1 may be able to articulate (pivot).

FIG. 4 is an enlarged isometric view of the distal end of the surgicaltool of FIG. 1 .

FIG. 5 is an exploded view of a portion of the end effector of FIG. 4 .

FIG. 6 is a cross-sectional side view of the end effector of FIG. 5 asassembled.

DETAILED DESCRIPTION

The present disclosure is related to robotic surgical systems and, moreparticularly, to surgical instruments having an end effector thatincorporates a dual axle construction where one axle resides inside ahollow outer axle to increase the bearing surface and reduce galling.

Embodiments discussed herein describe surgical instruments thatincorporate cable-driven end effectors with an improved axle that helpsmitigate galling. One example end effector includes a distal clevis, anaxle mounted to the distal clevis, a first jaw holder and correspondingfirst jaw member rotatably mounted to the axle, and a second jaw holderand corresponding second jaw member rotatably mounted to the axle. Asleeve axle radially interposes the axle and the jaw holders. The sleeveaxle has a first end, a second end, and a central passageway extendingbetween the first and second ends. The axle may be received within thecentral passageway and the sleeve axle is rotatable relative to theaxle. Various portions of the axle and the sleeve axle may also becoated or otherwise include a wear-resistant substance to mitigate wearand friction.

FIG. 1 is a block diagram of an example robotic surgical system 100 thatmay incorporate some or all of the principles of the present disclosure.As illustrated, the system 100 can include at least one mastercontroller 102 a and at least one arm cart 104, although the arm cart104 is not necessarily required. The arm cart 104 may be mechanicallyand/or electrically coupled to a robotic manipulator and, moreparticularly, to one or more robotic arms 106 or “tool drivers”. Eachrobotic arm 106 may include and otherwise provide a location formounting one or more surgical tools or instruments 108 for performingvarious surgical tasks on a patient 110. Operation of the robotic arms106 and instruments 108 may be directed by a clinician 112 a (e.g., asurgeon) from the master controller 102 a.

In some embodiments, a second master controller 102 b (shown in dashedlines) operated by a second clinician 112 b may also direct operation ofthe robotic arms 106 and instruments 108 in conjunction with the firstclinician 112 a. In such embodiments, for example, each clinician 102a,b may control different robotic arms 106 or, in some cases, completecontrol of the robotic arms 106 may be passed between the clinicians 102a,b. In some embodiments, additional arm carts (not shown) havingadditional robotic arms (not shown) may be utilized during surgery on apatient 110, and these additional robotic arms may be controlled by oneor more of the master controllers 102 a,b.

The arm cart 104 and the master controllers 102 a,b may be incommunication with one another via a communications link 114, which maybe any type of wired or wireless telecommunications means configured tocarry a variety of communication signals (e.g., electrical, optical,infrared, etc.) according to any communications protocol. In someapplications, for example, there is a tower with ancillary equipment andprocessing cores designed to drive the robotic arms 106.

The master controllers 102 a,b generally include one or more physicalcontrollers that can be grasped by the clinicians 112 a,b andmanipulated in space while the surgeon views the procedure via a stereodisplay. The physical controllers generally comprise manual inputdevices movable in multiple degrees of freedom, and which often includean actuatable handle for actuating the surgical instrument(s) 108, forexample, for opening and closing opposing jaws, applying an electricalpotential (current) to an electrode, or the like. The master controllers102 a,b can also include an optional feedback meter viewable by theclinicians 112 a,b via a display to provide a visual indication ofvarious surgical instrument metrics, such as the amount of force beingapplied to the surgical instrument (i.e., a cutting instrument ordynamic clamping member).

Example implementations of robotic surgical systems, such as the system100, are disclosed in U.S. Pat. No. 7,524,320, the contents of which areincorporated herein by reference. The various particularities of suchdevices will not be described in detail herein beyond that which may benecessary to understand the various embodiments and forms of the variousembodiments of robotic surgery apparatus, systems, and methods disclosedherein.

FIG. 2 is side view of an example surgical tool 200 that may incorporatesome or all of the principles of the present disclosure. The surgicaltool 200 may be the same as or similar to the surgical instrument(s) 108of FIG. 1 and, therefore, may be used in conjunction with a roboticsurgical system, such as the robotic surgical system 100 of FIG. 1 .Accordingly, the surgical tool 200 may be designed to be releasablycoupled to a tool driver included in the robotic surgical system 100. Inother embodiments, however, the surgical tool 200 may be adapted for usein a manual or hand-operated manner, without departing from the scope ofthe disclosure.

As illustrated, the surgical tool 200 includes an elongated shaft 202,an end effector 204, a wrist 206 (alternately referred to as a “wristjoint”) that couples the end effector 204 to the distal end of the shaft202, and a drive housing 208 coupled to the proximal end of the shaft202. In applications where the surgical tool is used in conjunction witha robotic surgical system (e.g., the robotic surgical system 100 of FIG.1 ), the drive housing 208 can include coupling features that releasablycouple the surgical tool 200 to the robotic surgical system.

The terms “proximal” and “distal” are defined herein relative to arobotic surgical system having an interface configured to mechanicallyand electrically couple the surgical tool 200 (e.g., the housing 208) toa robotic manipulator. The term “proximal” refers to the position of anelement closer to the robotic manipulator and the term “distal” refersto the position of an element closer to the end effector 204 and thusfurther away from the robotic manipulator. Alternatively, in manual orhand-operated applications, the terms “proximal” and “distal” aredefined herein relative to a user, such as a surgeon or clinician. Theterm “proximal” refers to the position of an element closer to the userand the term “distal” refers to the position of an element closer to theend effector 204 and thus further away from the user. Moreover, the useof directional terms such as above, below, upper, lower, upward,downward, left, right, and the like are used in relation to theillustrative embodiments as they are depicted in the figures, the upwardor upper direction being toward the top of the corresponding figure andthe downward or lower direction being toward the bottom of thecorresponding figure.

During use of the surgical tool 200, the end effector 204 is configuredto move (pivot) relative to the shaft 202 at the wrist 206 to positionthe end effector 204 at desired orientations and locations relative to asurgical site. The housing 208 includes (contains) various mechanismsdesigned to control operation of various features associated with theend effector 204 (e.g., clamping, firing, rotation, articulation, energydelivery, etc.). In at least some embodiments, the shaft 202, and hencethe end effector 204 coupled thereto, is configured to rotate about alongitudinal axis A₁ of the shaft 202. In such embodiments, at least oneof the mechanisms included (housed) in the housing 208 is configured tocontrol rotational movement of the shaft 202 about the longitudinal axisA₁.

The surgical tool 200 can have any of a variety of configurationscapable of performing at least one surgical function. For example, thesurgical tool 200 may include, but is not limited to, forceps, agrasper, a needle driver, scissors, an electro cautery tool, a stapler,a clip applier, a hook, a spatula, a suction tool, an irrigation tool,an imaging device (e.g., an endoscope or ultrasonic probe), or anycombination thereof. In some embodiments, the surgical tool 200 may beconfigured to apply energy to tissue, such as radio frequency (RF)energy.

The shaft 202 is an elongate member extending distally from the housing208 and has at least one lumen extending therethrough along its axiallength. In some embodiments, the shaft 202 may be fixed to the housing208, but could alternatively be rotatably mounted to the housing 208 toallow the shaft 202 to rotate about the longitudinal axis A₁. In yetother embodiments, the shaft 202 may be releasably coupled to thehousing 208, which may allow a single housing 208 to be adaptable tovarious shafts having different end effectors.

The end effector 204 can have a variety of sizes, shapes, andconfigurations. In the illustrated embodiment, the end effector 204comprises surgical scissors that include opposing jaws 210, 212(alternately referred to as “blades”) configured to move (articulate)between open and closed positions. As will be appreciated, however, theopposing jaws 210, 212 may alternatively form part of other types of endeffectors such as, but not limited to, a tissue grasper, a clip applier,a needle driver, a babcock including a pair of opposed grasping jaws,bipolar jaws (e.g., bipolar Maryland grasper, forceps, a fenestratedgrasper, etc.), etc. One or both of the jaws 210, 212 may be configuredto pivot at the wrist 206 to articulate the end effector 204 between theopen and closed positions.

FIG. 3 illustrates the potential degrees of freedom in which the wrist206 may be able to articulate (pivot). The wrist 206 can have any of avariety of configurations. In general, the wrist 206 comprises a jointconfigured to allow pivoting movement of the end effector 204 relativeto the shaft 202. The degrees of freedom of the wrist 206 arerepresented by three translational variables (i.e., surge, heave, andsway), and by three rotational variables (i.e., Euler angles or roll,pitch, and yaw). The translational and rotational variables describe theposition and orientation of a component of a surgical system (e.g., theend effector 204) with respect to a given reference Cartesian frame. Asdepicted in FIG. 3 , “surge” refers to forward and backwardtranslational movement, “heave” refers to translational movement up anddown, and “sway” refers to translational movement left and right. Withregard to the rotational terms, “roll” refers to tilting side to side,“pitch” refers to tilting forward and backward, and “yaw” refers toturning left and right.

The pivoting motion can include pitch movement about a first axis of thewrist 206 (e.g., X-axis), yaw movement about a second axis of the wrist206 (e.g., Y-axis), and combinations thereof to allow for 360°rotational movement of the end effector 204 about the wrist 206. Inother applications, the pivoting motion can be limited to movement in asingle plane, e.g., only pitch movement about the first axis of thewrist 206 or only yaw movement about the second axis of the wrist 206,such that the end effector 204 moves only in a single plane.

Referring again to FIG. 2 , the surgical tool 200 may also include aplurality of drive cables (obscured in FIG. 2 ) that form part of acable driven motion system configured to facilitate movement andarticulation of the end effector 204 relative to the shaft 202. Moving(actuating) at least some of the drive cables moves the end effector 204between an unarticulated position and an articulated position. The endeffector 204 is depicted in FIG. 2 in the unarticulated position where alongitudinal axis A₂ of the end effector 204 is substantially alignedwith the longitudinal axis A₁ of the shaft 202, such that the endeffector 204 is at a substantially zero angle relative to the shaft 202.Due to factors such as manufacturing tolerance and precision ofmeasurement devices, the end effector 204 may not be at a precise zeroangle relative to the shaft 202 in the unarticulated position, butnevertheless be considered “substantially aligned” thereto. In thearticulated position, the longitudinal axes A₁, A₂ would be angularlyoffset from each other such that the end effector 204 is at a non-zeroangle relative to the shaft 202.

FIG. 4 is an enlarged isometric view of the distal end of the surgicaltool 200 of FIG. 2 . More specifically, FIG. 4 depicts enlarged views ofthe end effector 204 and the wrist 206, with the end effector 204 in theunarticulated position. The wrist 206 operatively couples the endeffector 204 to the shaft 202 (FIG. 2 ). In the illustrated embodiment,however, a shaft adapter 400 may be directly coupled to the wrist 206and otherwise interpose the shaft 202 and the wrist 206. In otherembodiments, the shaft adapter 400 may be omitted and the shaft 202 mayinstead be directly coupled to the wrist 206, without departing from thescope of the disclosure. As used herein, the term “operatively couple”refers to a direct or indirect coupling engagement. Accordingly, thewrist 206 may be operatively coupled to the shaft 202 either through adirect coupling engagement where the wrist 206 is directly coupled tothe distal end of the shaft 202, or an indirect coupling engagementwhere the shaft adapter 400 interposes the wrist 206 and the distal endof the shaft 202.

To operatively couple the end effector 204 to the shaft 202 (e.g., viathe shaft adapter 400), the wrist 206 includes a distal clevis 402 a anda proximal clevis 402 b. The end effector 204 (i.e., the jaws 210, 212)is rotatably mounted to the distal clevis 402 a at a first axle 404 a,the distal clevis 402 a is rotatably mounted to the proximal clevis 402b at a second axle 404 b, and the proximal clevis 402 b is coupled to adistal end 406 of the shaft adapter 400 (or alternatively the distal endof the shaft 202 of FIG. 2 ).

The wrist 206 provides a first pivot axis P₁ that extends through thefirst axle 404 a and a second pivot axis P₂ that extends through thesecond axle 404 b. The first pivot axis P₁ is substantiallyperpendicular (orthogonal) to the longitudinal axis A₂ of the endeffector 204, and the second pivot axis P₂ is substantiallyperpendicular (orthogonal) to both the longitudinal axis A₂ and thefirst pivot axis P₁. Movement about the first pivot axis P₁ provides“yaw” articulation of the end effector 204, and movement about thesecond pivot axis P₂ provides “pitch” articulation of the end effector204. In the illustrated embodiment, the jaws 210, 212 are mounted at thefirst pivot axis P₁ thereby allowing the jaws 210, 212 to pivot relativeto each other to open and close the end effector 204 or alternativelypivot in tandem to articulate the orientation of the end effector 204.

A plurality of drive cables, shown as drive cables 408 a, 408 b, 408 c,and 408 d, extend longitudinally within a lumen 410 defined by the shaftadapter 400 (and/or the shaft 202 of FIG. 2 ) and pass through the wrist206 to be operatively coupled to the end effector 204. While four drivecables 408 a-d are depicted in FIG. 4 , more or less than four drivecables 408 a-d may be included, without departing from the scope of thedisclosure.

The drive cables 408 a-d form part of the cable driven motion systembriefly described above, and may be referred to and otherwisecharacterized as cables, bands, lines, cords, wires, ropes, strings,twisted strings, elongate members, etc. The drive cables 408 a-d can bemade from a variety of materials including, but not limited to, metal(e.g., tungsten, stainless steel, etc.) or a polymer. Example drivecables are described in U.S. Patent Pub. No. 2015/0209965 entitled“Compact Robotic Wrist,” and U.S. Patent Pub. No. 2015/0025549 entitled“Hyperdexterous Surgical System,” the contents of which are herebyincorporated by reference. The lumen 410 can be a single lumen, asillustrated, or can alternatively comprise a plurality of independentlumens that each receive one or more of the drive cables 408 a-d.

The drive cables 408 a-d extend proximally from the end effector 204 tothe drive housing 208 (FIG. 2 ) where they are operatively coupled tovarious actuation mechanisms or devices housed (contained) therein tofacilitate longitudinal movement (translation) of the drive cables 408a-d within the lumen 410. Selective actuation of all or a portion of thedrive cables 408 a-d causes the end effector 204 (e.g., one or both ofthe jaws 210, 212) to articulate (pivot) relative to the shaft 202. Morespecifically, selective actuation causes a corresponding drive cable 408a-d to translate longitudinally within the lumen 410 and thereby causepivoting movement of the end effector 204. One or more drive cables 408a-d, for example, may translate longitudinally to cause the end effector204 to articulate (e.g., both of the jaws 210, 212 angled in a samedirection), to cause the end effector 204 to open (e.g., one or both ofthe jaws 210, 212 pivot away from the other), or to cause the endeffector 204 to close (e.g., one or both of the jaws 210, 212 pivottoward the other).

Moving the drive cables 408 a-d can be accomplished in a variety ofways, such as by triggering an associated actuator or mechanismoperatively coupled to or housed within the drive housing 208 (FIG. 2 ).Moving a given drive cable 408 a-d constitutes applying tension (i.e.,pull force) to the given drive cable 408 a-d in a proximal direction,which causes the given drive cable 408 a-d to translate and therebycause the end effector 204 to move (articulate) relative to the shaft202.

The wrist 206 includes a first plurality of pulleys 412 a and a secondplurality of pulleys 412 b, each configured to interact with andredirect the drive cables 408 a-d for engagement with the end effector204. The first plurality of pulleys 412 a is mounted to the proximalclevis 402 b at the second axle 404 b and the second plurality ofpulleys 412 b is also mounted to the proximal clevis 402 b but at athird axle 404 c located proximal to the second axle 404 b. The firstand second pluralities of pulleys 412 a,b cooperatively redirect thedrive cables 408 a-d through an “S” shaped pathway before the drivecables 408 a-d are operatively coupled to the end effector 204.

In at least one embodiment, one pair of drive cables 408 a-d isoperatively coupled to each jaw 210, 212 and configured to“antagonistically” operate the corresponding jaw 210, 212. In theillustrated embodiment, for example, the first and second drive cables408 a,b are coupled with a connector (not shown) at the first jaw 210,and the third and fourth drive cables 408 c,d are coupled with aconnector (not shown) at the second jaw 212. Consequently, actuation ofthe first drive cable 408 a pivots the first jaw 210 about the firstpivot axis P₁ toward the open position, and actuation of the seconddrive cable 408 b pivots the first jaw 210 about the first pivot axis P₁in the opposite direction and toward the closed position. Similarly,actuation of the third drive cable 408 c pivots the second jaw 212 aboutthe first pivot axis P₁ toward the open position, while actuation of thefourth drive cable 408 d pivots the second jaw 212 about the first pivotaxis P₁ in the opposite direction and toward the closed position.

Accordingly, the drive cables 408 a-d may be characterized or otherwisereferred to as “antagonistic” cables that cooperatively (yetantagonistically) operate to cause relative or tandem movement of thefirst and second jaws 210, 212. When the first drive cable 408 a isactuated (moved), the second drive cable 408 b naturally follows ascoupled to the first drive cable 408 a, and when the third drive cable408 c is actuated, the fourth drive cable 408 d naturally follows ascoupled to the third drive cable 408 c, and vice versa.

The end effector 204 further includes a first jaw holder 414 a and asecond jaw holder 414 b laterally offset from the first jaw holder 414a. The first jaw holder 414 a is mounted to the first axle 404 a andconfigured to receive and seat the first jaw 210 such that movement(rotation) of the first jaw holder 414 a about the first pivot axis P₁correspondingly moves (rotates) the first jaw 210. The first jaw holder414 a may also provide and otherwise define a first pulley 416 aconfigured to receive and seat one or more drive cables, such as thefirst and second drive cables 408 a,b to effect such movement(rotation). The second jaw holder 414 b is similarly mounted to thefirst axle 404 a and is configured to receive and seat the second jaw212 such that movement (rotation) of the second jaw holder 414 b aboutthe first pivot axis P₁ correspondingly moves (rotates) the second jaw212. The second jaw holder 414 b may also provide and otherwise define asecond pulley 416 b configured to receive and seat one or more drivecables, such as the third and fourth drive cables 408 c,d, to effectsuch movement (rotation).

The term “jaw holder,” as used herein, is intended to apply to a varietyof types of end effectors having opposing jaws or blades that arerotatably pivotable (movable) relative to one another. In theillustrated embodiment, the jaws 210, 212 comprise opposing scissorblades of a surgical scissors end effector. Accordingly, the jaw holders414 a,b may alternately be referred to as “blade holders”. In otherembodiments, however, the jaws 210, 212 may alternatively compriseopposing jaws used in a grasper end effector, or the like, and the term“jaw holder” similarly applies, without departing from the scope of thedisclosure. Moreover, the term “holder” in “jaw holder” may be replacedwith “mount,” “drive member,” or “actuation member.”

FIG. 5 is an exploded view of a portion of the end effector 204,according to one or more embodiments of the disclosure. Morespecifically, FIG. 5 depicts the distal clevis 402 a, the first andsecond jaw members 210, 212 mounted to their respective first and secondjaw holders 414 a,b, and the first axle 404 a.

As illustrated, the distal clevis 402 a includes a firstdistally-extending arm 502 a and a second distally-extending arm 502 boffset from the first distally-extending arm 502 a. The first arm 502 adefines a first aperture 504 a configured to receive and seat one end ofthe first axle 404 a, and the second arm 502 b defines a second aperture504 b configured to receive and seat the opposite end of the first axle404 a.

The first and second jaw members 210, 212 may be mounted to the firstand second jaw holders 414 a,b, respectively, such that movement of theparticular jaw holder 414 a,b will correspondingly move the mounted jawmember 210, 212. In the illustrated embodiment, for example, the firstand second jaw holders 414 a,b may each provide or otherwise define ajaw recess 506 sized to receive and seat the jaw members 210, 212. Thejaw holders 414 a,b may also each define a central aperture 508 throughwhich the first axle 404 a may extend to rotatably mount the jaw members210, 212 to the distal clevis 402 a.

In the illustrated embodiment, the end effector 204 may further includea sleeve axle 510 that may be designed to assume some or all of thebearing stress caused by independent rotation of the jaw holders 414 a,bduring operation. As illustrated, the sleeve axle 510 comprises agenerally hollow and cylindrical body 512 having a first end 514 a and asecond end 514 b opposite the first end 514 a. A central passageway 516is defined in the body 512 and extends between the first and second ends514 a,b. The central passageway 516 may be sized or otherwise configuredto receive the first axle 404 a therein. When the end effector 204 isfully assembled, the sleeve axle 510 interposes the first axle 404 a andthe jaw holders 414 a,b. Accordingly, the sleeve axle 510 may mitigateor entirely eliminate galling on the first axle 404 a, which couldotherwise limit the useful service life of the end effector 204.

In some embodiments, as illustrated, the sleeve axle 510 may provide orotherwise define an enlarged-diameter head 518 at the second end 514 bto help properly position the sleeve axle 510 for operation. Morespecifically, the sleeve axle 510 may be extendable through thecoaxially aligned central apertures 508 of each jaw holder 414 a,b, andthe enlarged-diameter head 518 may be sized to be received into an endrecess 520 defined on the second jaw holder 414 b. In at least oneembodiment, the depth of the end recess 520 may allow theenlarged-diameter head 518 to be received in a flush-mount arrangementwith the remaining portions of the second jaw holder 414 a, but mayalternatively protrude a short distance to act as a bearing against aninner surface of the distal clevis 402 a.

To assemble the end effector 204, the sleeve axle 510 is extendedthrough the coaxially aligned central apertures 508 of each jaw holder414 a,b until the enlarged-diameter head 518 is received within the endrecess 520. In some embodiments, the sleeve axle 510 may be coupled tothe first jaw holder 414 a to secure the sleeve axle 510 in place. Inconjunction with the enlarged-diameter head 518 being received withinthe end recess 520, securing the sleeve axle 510 to the first jaw holder414 a may essentially couple the first jaw holder 414 a to the secondjaw holder 414 b.

The first and second jaw holders 414 a,b may then be positioned in anopening 522 defined between the opposing arms 502 a,b of the distalclevis 402 a. The first axle 404 a may then be progressively extendedthrough the first aperture 504 a in the first arm 502 a, the centralpassageway 516 of the sleeve axle 510, and the second aperture 504 b inthe second arm 502 b. One or both ends of the first axle 404 a may thenbe secured to the distal clevis 402 a at the first or second apertures504 a,b to secure the first axle 404 a to the distal clevis 402 a.

FIG. 6 is a cross-sectional side view of the end effector 204 of FIG. 5as assembled, according to one or more embodiments. As illustrated, thesleeve axle 510 generally interposes the first axle 404 a and the firstand second jaw holders 414 a,b. More specifically, the sleeve axle 510is extended through the coaxially aligned central apertures 508 of thejaw holders 414 a,b and the enlarged-diameter head 518 is received intothe end recess 520 of the second jaw holder 414 b. Moreover, the firstaxle 404 a extends through the central passageway 516 of the sleeve axle510.

The sleeve axle 510 may be secured to the first jaw holder 414 a via avariety of means. In some embodiments, for example, the sleeve axle 510may be welded or brazed to the first jaw holder 414 a at the first end514 a, as shown by the arrows W. In other embodiments, however, thesleeve axle 510 may be threaded to the first jaw holder 414 a via amating threaded engagement, without departing from the scope of thedisclosure.

In some embodiments, a compressive load (force) may be applied to thefirst jaw holder 414 a along the sleeve axle 510 as the sleeve axle 510is secured to the first jaw holder 414 a. The compressive load may forcethe enlarged-diameter head 518 against the second jaw holder 414 b atthe end recess 520, and thereby remove any gaps between the jaw holders414 a,b to provide a zero tolerance stack. This may prove advantageousin trapping the jaw members 210, 212 within the assembly such that thejaw members 210, 212 need not be welded to the respective jaw holders414 a,b. Moreover, securing the sleeve axle 510 to the first jaw holder414 a while a compressive load (force) is applied ensures that opposingaxial bearing surfaces 600 of the jaw members 210, 212 are maintainedparallel to one another during operation. This may prove advantageous inassuring face-to-face contact at the midline between of the jaw members210, 212 while opening and closing the jaw members 210, 212.

Since the sleeve axle 510 is secured to the first jaw holder 414 a,movement (articulation) of the first jaw holder 414 a correspondinglyrotates the sleeve axle 510 about the first pivot axis P₁ In contrast,the second jaw holder 414 b may be free to move (articulate) relative tothe sleeve axle 510 during operation. Consequently, as the scissoringaction of the jaw members 210, 212 takes place, the sleeve axle 510assumes the bearing stress at the interface between the sleeve axle 510and the second jaw holder 414 b.

In some embodiments, the end effector 204 may include a wear-resistantsubstance 602 (shown as dashed lines) provided at the radial interfacebetween the sleeve axle 510 and the second jaw holder 414 b to reducefriction and wear. In one embodiment, the wear-resistant substance 602may comprise a material coated on the outer radial surface of the sleeveaxle 510, but could alternatively (or in addition thereto) comprise amaterial coated on the inner radial surface of the second jaw holder 414b at the central aperture 508. In yet other embodiments, thewear-resistant substance 602 may comprise a low-friction bearingmaterial or structure that interposes the sleeve axle 510 and the secondjaw holder 414 b. The wear-resistant substance 602 may comprise alow-friction material such as, but not limited to, a diamond-like carbon(DLC), an ultra-hard material (e.g., polycrystalline diamond,polycrystalline cubic boron nitride, or impregnated diamond), alubricant (e.g., KRYTOX™ brand synthetic lubricant), a dry film coating(e.g., TEFLON®, graphite, etc.), or any combination thereof.Alternatively, the second jaw holder 414 b may be machined out of aspinodal bronze or another material that offers good galling resistanceand strength against stainless steel, for example.

In some embodiments, the wear-resistant substance 602 may also beprovided at the axial interface between the sleeve axle 510 and thesecond jaw holder 414 b. More particularly, the wear-resistant substance602 may extend to the axial interface between the enlarged-diameter head518 and the end recess 520 to reduce friction and wear at that locationas the sleeve axle 510 rotates relative to the second jaw holder 414 b,and vice versa.

The first axle 404 a supports the jaw holders 414 a,b and the sleeveaxle 510 on the distal clevis 402 a and thereby controls the yaw motionof the end effector 204 when the jaw members 210, 212 move in unison.More specifically, the first axle 404 a extends through the centralpassageway 516 of the sleeve axle 510 and its opposing ends are receivedwithin the first and second apertures 504 a,b, respectively, of thedistal clevis 402 a. In some embodiments, one or both ends of the firstaxle 404 a may be secured to the distal clevis 402 a at the first orsecond apertures 504 a,b, respectively.

To secure the first axle 404 a to the distal clevis 402 a, one or bothends of the first axle 404 a may be welded or brazed to the distalclevis 402 a at the first or second apertures 504 a,b. In otherembodiments, one end of the first axle 404 a may be threaded to thecorresponding aperture 504 a,b. In yet other embodiments, one or both ofthe ends of the first axle 404 a may be secured to the correspondingapertures 504 a,b by orbital riveting the outer surface of the ends ofthe first axle 404 a. In even further embodiments, one or both ends ofthe first axle 404 a may be received within the corresponding aperture504 a,b via an interference or shrink fit.

Since the first axle 404 a is secured to the distal clevis 402 a, thejaw holders 414 a,b and the sleeve axle 510 may each be able to move(articulate) relative to the first axle 404 a about the first pivot axisP₁ Having the sleeve axle 510 interpose the first axle 404 a and the jawholders 414 a,b effectively spreads the bearing contact over the entireaxial length of the first axle 404 a via movement of the sleeve axle510.

In some embodiments, a wear-resistant substance 604 (shown as dashedlines) may be provided at the interface between the first axle 404 a andthe sleeve axle 510 to reduce friction and wear. The wear-resistantsubstance 604 may comprise similar materials or structures as thewear-resistant substance 602 mentioned above. The wear-resistantsubstance 604 may comprise a material coated on the outer radial surfaceof the first axle 404 a, or alternatively (or in addition thereto) onthe inner radial surface of the sleeve axle 510. In other embodiments,the wear-resistant substance 604 may comprise a low-friction bearingmaterial or structure interposing the first axle 404 a and the sleeveaxle 510.

Embodiments disclosed herein include:

A. An end effector that includes a distal clevis, an axle mounted to thedistal clevis, a first jaw holder and corresponding first jaw memberrotatably mounted to the axle, a second jaw holder and correspondingsecond jaw member rotatably mounted to the axle, and a sleeve axlehaving a first end, a second end, and a central passageway extendingbetween the first and second ends, wherein the axle is received withinthe central passageway and the sleeve axle is rotatable relative to theaxle.

B. A surgical tool that includes a drive housing, an elongate shaft thatextends from the drive housing, a wrist operatively coupled to a distalend of the shaft and having a distal clevis and an axle mounted to thedistal clevis, an end effector having a first jaw holder andcorresponding first jaw member rotatably mounted to the axle and asecond jaw holder and corresponding second jaw member rotatably mountedto the axle, and a sleeve axle radially interposing the first and secondjaw holders and the axle and rotatable relative to the axle.

C. A method of operating a surgical tool that includes positioning thesurgical tool adjacent a patient for operation, the surgical toolincluding a drive housing, an elongate shaft that extends from the drivehousing, a wrist operatively coupled to a distal end of the shaft andhaving a distal clevis and an axle mounted to the distal clevis, an endeffector having a first jaw holder and corresponding first jaw memberrotatably mounted to the axle and a second jaw holder and correspondingsecond jaw member rotatably mounted to the axle, and a sleeve axleradially interposing the first and second jaw holders and the axle androtatable relative to the axle. The method further includingarticulating at least one of the first and second jaw members about theaxle, and mitigating galling of the axle with the sleeve axle.

Each of embodiments A, B, and C may have one or more of the followingadditional elements in any combination: Element 1: wherein the sleeveaxle is secured to the first jaw holder such that movement of the firstjaw holder causes the sleeve axle to rotate. Element 2: wherein thefirst end of the sleeve axle is welded or brazed to the first jawholder. Element 3: further comprising a wear-resistant substanceprovided at a radial interface between the sleeve axle and the secondjaw holder. Element 4: wherein the wear-resistant substance comprises amaterial coated on one or both of an outer radial surface of the sleeveaxle and an inner radial surface of the second jaw holder. Element 5:further comprising an enlarged-diameter head provided at the second endand receivable within an end recess defined on the second jaw holder.Element 6: further comprising a wear-resistant substance provided at anaxial interface between the enlarged-diameter head and the end recess.Element 7: further comprising a wear-resistant substance provided at aninterface between the first axle and the sleeve axle. Element 8: whereinthe wear-resistant substance comprises a material coated on one or bothof an outer radial surface of the first axle and an inner radial surfaceof the sleeve axle. Element 9: wherein opposing ends of the first axleare received within corresponding apertures defined in the distalclevis, and wherein one or both of the opposing ends are secured to thedistal clevis at the corresponding apertures. Element 10: wherein theone or both of the opposing ends are secured to the distal clevis by atleast one of welding, brazing, a threaded engagement, orbital rivetingan interference fit, and a shrink fit.

Element 11: wherein the sleeve axle comprises a cylindrical body havinga first end, a second end, and a central passageway extending betweenthe first and second ends, and wherein the axle extends through thecentral passageway. Element 12: wherein the sleeve axle is secured tothe first jaw holder such that movement of the first jaw holder causesthe sleeve axle to rotate. Element 13: further comprising anenlarged-diameter head provided at the second end and receivable withinan end recess defined on the second jaw holder. Element 14: furthercomprising a wear-resistant substance provided at an axial interfacebetween the enlarged-diameter head and the end recess, wherein thewear-resistant substance comprises a low-friction material selected fromthe group consisting of a diamond-like carbon coating, an ultra-hardmaterial, a lubricant, a dry film coating, and any combination thereof.Element 15: further comprising a wear-resistant substance provided at aradial interface between the sleeve axle and the second jaw holder,wherein the wear-resistant substance comprises a low-friction materialselected from the group consisting of a diamond-like carbon coating, anultra-hard material, a lubricant, a dry film coating, and anycombination thereof. Element 16: further comprising a wear-resistantsubstance provided at an interface between the first axle and the sleeveaxle, wherein the wear-resistant substance comprises a low-frictionmaterial selected from the group consisting of a diamond-like carboncoating, an ultra-hard material, a lubricant, a dry film coating, andany combination thereof. Element 17: wherein the second jaw holder ismade of a material having a low galling threshold against stainlesssteel.

By way of non-limiting example, exemplary combinations applicable to A,B, and C include: Element 1 with Element 2; Element 3 with Element 4;Element 5 with Element 6; Element 7 with Element 8; Element 9 withElement 10; Element 11 with Element 12; Element 11 with Element 13; andElement 13 with Element 14.

Therefore, the disclosed systems and methods are well adapted to attainthe ends and advantages mentioned as well as those that are inherenttherein. The particular embodiments disclosed above are illustrativeonly, as the teachings of the present disclosure may be modified andpracticed in different but equivalent manners apparent to those skilledin the art having the benefit of the teachings herein. Furthermore, nolimitations are intended to the details of construction or design hereinshown, other than as described in the claims below. It is thereforeevident that the particular illustrative embodiments disclosed above maybe altered, combined, or modified and all such variations are consideredwithin the scope of the present disclosure. The systems and methodsillustratively disclosed herein may suitably be practiced in the absenceof any element that is not specifically disclosed herein and/or anyoptional element disclosed herein. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps. Allnumbers and ranges disclosed above may vary by some amount. Whenever anumerical range with a lower limit and an upper limit is disclosed, anynumber and any included range falling within the range is specificallydisclosed. In particular, every range of values (of the form, “fromabout a to about b,” or, equivalently, “from approximately a to b,” or,equivalently, “from approximately a-b”) disclosed herein is to beunderstood to set forth every number and range encompassed within thebroader range of values. Also, the terms in the claims have their plain,ordinary meaning unless otherwise explicitly and clearly defined by thepatentee. Moreover, the indefinite articles “a” or “an,” as used in theclaims, are defined herein to mean one or more than one of the elementsthat it introduces. If there is any conflict in the usages of a word orterm in this specification and one or more patent or other documentsthat may be incorporated herein by reference, the definitions that areconsistent with this specification should be adopted.

As used herein, the phrase “at least one of” preceding a series ofitems, with the terms “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” allows a meaning that includesat least one of any one of the items, and/or at least one of anycombination of the items, and/or at least one of each of the items. Byway of example, the phrases “at least one of A, B, and C” or “at leastone of A, B, or C” each refer to only A, only B, or only C; anycombination of A, B, and C; and/or at least one of each of A, B, and C.

What is claimed is:
 1. An end effector, comprising: a distal clevis; anaxle mounted to the distal clevis; a first jaw holder and correspondingfirst jaw member rotatably mounted to the axle; a second jaw holder andcorresponding second jaw member rotatably mounted to the axle; and acylindrical sleeve axle having opposing first and second ends anddefining a central passageway extending between the opposing first andsecond ends, the sleeve axle providing a continuously straight anduninterrupted outer surface extending entirely between the opposingfirst and second ends, wherein the first end is housed within the firstjaw holder and the second end is housed within the second jaw holder,wherein the axle is received within the central passageway and thesleeve axle is rotatable relative to the axle.
 2. The end effector ofclaim 1, wherein the sleeve axle is secured to the first jaw holder suchthat movement of the first jaw holder causes the sleeve axle to rotate.3. The end effector of claim 2, wherein the first end of the sleeve axleis welded or brazed to the first jaw holder.
 4. The end effector ofclaim 1, further comprising a wear-resistant substance provided at aradial interface between the sleeve axle and the second jaw holder. 5.The end effector of claim 4, wherein the wear-resistant substancecomprises a material coated on one or both of an outer radial surface ofthe sleeve axle and an inner radial surface of the second jaw holder. 6.The end effector of claim 1, wherein a head is provided at the secondend of the sleeve axle and exhibits a diameter larger than a diameter ofremaining portions of the sleeve axle, and wherein the head is receivedwithin an end recess defined on the second jaw holder.
 7. The endeffector of claim 6, further comprising a wear-resistant substanceprovided at an axial interface between the head and the end recess. 8.The end effector of claim 1, further comprising a wear-resistantsubstance provided at an interface between the axle and the sleeve axle.9. The end effector of claim 8, wherein the wear-resistant substancecomprises a material coated on one or both of an outer radial surface ofthe axle and an inner radial surface of the sleeve axle.
 10. The endeffector of claim 1, wherein opposing ends of the axle are receivedwithin corresponding apertures defined in the distal clevis, and whereinone or both of the opposing ends of the axle are secured to the distalclevis at the corresponding apertures and thereby prevent the axle fromrotating relative to the distal clevis.
 11. The end effector of claim10, wherein the one or both of the opposing ends of the axle are securedto the distal clevis by at least one of welding, brazing, a threadedengagement, orbital riveting an interference fit, and a shrink fit. 12.The end effector of claim 1, wherein the first jaw holder provides afirst pulley operable to receive and seat one or more first drivecables, and the second jaw holder provides a second pulley operable toreceive and seat one or more second drive cables, and wherein actuationof the one or more first drive cables and the one or more second drivecables causes the corresponding first and second jaw members to pivotrelative to one another.
 13. A surgical tool, comprising: a drivehousing; an elongate shaft that extends from the drive housing; a wristoperatively coupled to a distal end of the shaft and having a distalclevis and an axle mounted to the distal clevis; an end effector havinga first jaw holder and corresponding first jaw member rotatably mountedto the axle and a second jaw holder and corresponding second jaw memberrotatably mounted to the axle; and a cylindrical sleeve axle havingopposing first and second ends and defining a central passagewayextending between the opposing first and second ends, the sleeve axleproviding a continuously straight and uninterrupted outer surfaceextending entirely between the opposing first and second ends, whereinthe first end is housed within the first jaw holder and the second endis housed within the second jaw holder, wherein the sleeve axle radiallyinterposes the first and second jaw holders and the axle and isrotatable relative to the axle.
 14. The surgical tool of claim 13,wherein the axle extends through the central passageway.
 15. Thesurgical tool of claim 13, wherein the sleeve axle is secured to thefirst jaw holder such that movement of the first jaw holder causes thesleeve axle to rotate.
 16. The surgical tool of claim 13, wherein a headis provided at the second end of the sleeve axle and exhibits a diameterlarger than a diameter of remaining portions of the sleeve axle, andwherein the head is received within an end recess defined on the secondjaw holder.
 17. The surgical tool of claim 16, further comprising awear-resistant substance provided at an axial interface between the headand the end recess, wherein the wear-resistant substance comprises alow-friction material selected from the group consisting of adiamond-like carbon coating, an ultra-hard material, a lubricant, a dryfilm coating, and any combination thereof.
 18. The surgical tool ofclaim 13, further comprising a wear-resistant substance provided at aradial interface between the sleeve axle and the second jaw holder,wherein the wear-resistant substance comprises a low-friction materialselected from the group consisting of a diamond-like carbon coating, anultra-hard material, a lubricant, a dry film coating, and anycombination thereof.
 19. The surgical tool of claim 13, furthercomprising a wear-resistant substance provided at an interface betweenthe axle and the sleeve axle, wherein the wear-resistant substancecomprises a low-friction material selected from the group consisting ofa diamond-like carbon coating, an ultra-hard material, a lubricant, adry film coating, and any combination thereof.
 20. A method of operatinga surgical tool, comprising: positioning the surgical tool adjacent apatient for operation, the surgical tool including: a drive housing; anelongate shaft that extends from the drive housing; a wrist operativelycoupled to a distal end of the shaft and having a distal clevis and anaxle mounted to the distal clevis; an end effector having a first jawholder and corresponding first jaw member rotatably mounted to the axleand a second jaw holder and corresponding second jaw member rotatablymounted to the axle; and a cylindrical sleeve axle having opposing firstand second ends and defining a central passageway extending between theopposing first and second ends, the sleeve axle providing a continuouslystraight and uninterrupted outer surface extending entirely between theopposing first and second ends, wherein the first end is housed withinthe first jaw holder and the second end is housed within the second jawholder, and the axle is received within the central passageway such thatthe sleeve axle radially interposes the first and second jaw holders andthe axle; articulating at least one of the first and second jaw membersabout the axle, wherein the sleeve axle is rotatable relative to theaxle; and mitigating galling of the axle with the sleeve axle.